In an environment in which Machine-to-Machine (M2M) devices are connected to an M2M service provider (SP) through an access network provided by another entity, the M2M service provider effectively creates a service layer on top of the access network. This service layer is used to deliver services to the M2M devices through the access network, but doing so requires the use of device identifiers known to both the access network and the M2M SP network, for identifying the devices involved in such services. In the European Telecommunications Standards Institute (ETSI) M2M framework, the M2M SP interworks with the access network, for the M2M devices that have subscribed to the services provided by the M2M SP. This interworking is typically performed using an external identifier selected for that purpose. Other available identifiers include the Mobile Station International Subscriber Directory Number (MSISDN), the Internet Protocol Multimedia Public Identity (IMPU), etc.
External identifiers are typically allocated by the access network for respective M2M devices, and are used for interworking purposes between the access network and the service provider network. Use of the external identifier means that the access network does not have to share the IMSI or other such identifier, which is typically reserved for use as an access network private identity, and which is not used on external (public) interfaces, such as the interface with the service provider network.
The Third Generation Partnership Project (3GPP) R11 standards define external identifiers. As defined, an external identifier is associated only with MTC Device triggering procedures. However, the 3GPP specification does not describe how external networks can acquire the external identifier of a given M2M device for interworking purposes. Furthermore, the M2M ETSI standard does not consider the use of the MTC Device triggering procedure and the mechanism to acquire external identifiers from an access network, for triggering targeted M2M devices via the access network.